The thing is that a lot of Y2K vibes comics are done by people who were at best little kids in these years. Many not even born. They largely comprehend the 2000's through shared interests a kid might have with older people, like video games.
Scott Pilgrim is sort of a rosetta stone for these people because it's set in the 2000's, but filled with still-relevant game and nerd references that a younger person can relate to.Between that, and curated examples of the 2000's through images(often advertising images), music, and other scraps of pop culture relevant to their interests, they attempt to assemble something they feel matches the era.

The result is something like when Spongebob tries to throw a Texas party but only knows a few sayings and vague ideas. A themepark version of an era, viewed through the lens of a young kid.